Lubricant compositions



United States Patent LUBHCANT COMPOSITIONS Elliott S. Francis, Brackenridge, and Robert R. Shoemaker, Baldwin Township, Allegheny County, Pa., assignorsto Gulf Research & Development Company,

Pittsburgh, Pa., a corporation of Delaware No Drawing. Application December 27, 1951, Serial No. 263,698 4 Claims. (Cl. 252-49.9)

This invention relates to lubricant compositions and more particularly to improved marine engine oils.

In the lubrication of machinery such as marine steam engines and pneumatic tools in which the bearing surfaces at times encounter relatively large quantities of water there is danger that the lubricating oils supplied to these bearing surfaces may be displaced by water and that failure of the bearings will occur. If, however, the lubricating oils can readily emulsify the water, satisfactory lubrication will be maintained.

It is also necessary that a marine engine oil possess good Wick feed flow rate characteristics. Marine engine bearings are conventionally oiled through the use of oil cups fitted with syphon wicks which syphon the oil from the cups and deliver it through oil pipes to the bearings. Unless the marine engine oil possesses good wick feed fiow rate characteristics, the syphon wick Will'gurn up and inhibit the flow of oil to the bearing. It will then be diflicult to maintain adequate lubrication without excessive maintenance attention. In addition to the foregoing, it is desirable that the marine engine oil possess good oiliness and load-carrying properties.

Conventional marine engine oils of the past have comprised petroleum hydrocarbon oils compounded with a blown fatty oil, in particular, blown rapeseed oil. These oils possess good water emulsification properties, wick feed flow rate characteristics, oiliness and extreme pressure properties. However, due to the great increase in cost of rapeseed oil in recent years, it has been found desirable to substitute other additives for the blown rapeseed oil. In particular, We have endeavored to substitute an ester formed by the reaction of glycerol with the mixed acids prepared by the air oxidation of petrolatum for the blown rapeseed oil. This ester was found to confer excellent water emulsification properties upon the compounded oil. However, it was also found that the wick feed characteristics of the compounded oil containing this ester were not satisfactory. In fact, in many cases the wick feed characteristics of the compounded oil were poorer than those of the petroleum hydrocarbon oil by itself. Inasmuch as a marine engine oil should possess good wick feed flow rate characteristics, these compounded petroleum hydrocarbon oils containing solely the ester were not deemed satisfactory marine engine oils.

The present invention relates to a lubricant composition which possesses excellent wick feed flow rate characteristics, and excellent Water emulsification, oiliness, and load-carrying properties. The lubricant compositions of our invention comprise an ester formed by the reaction of glycerol with mixed acids prepared by the air oxidation of petrolatum, a phosphatide and a petroleum hydrocarbon oil having a viscosity at 210 F. of about 65 to 90 Saybolt Universal seconds in which the ester and phosphatide are present in an amount sufiicient to improve the wick feed flow rate characteristics of the oil. Preferably, the phosphatides used in our lubricant compositions should comprise lecithin and/or cephalin, with mixtures of lecithin appended claims, we mean to include alpha and beta lecithins and cephalins and the lecithins and cephalins and cephalin being the most suitable. The lubricant compositions of our invention usually contain about 0.5 to 10 per cent by weight of the ester and about 0.25 to 5 per 7 cent by weight of the phosphatide. The preferred compositions of our invention contain about 2 to 5 per cent by weight of the ester and about 0.5 to 3 per cent by weight of a mixture of lecithin and cephalin. Our most preferred composition contains about 2 per cent by weight of the ester and about 2 per cent by weight of a mixture of lecithin and cephalin.

By the term phosphatide as used herein and in the appended claims, We mean to include the pure phosphatides such as lecithin and cephalin and mixtures of phosphatides such as the commercially available mixtures containing lecithin and/or cephalin together with vegetable oils.

The lecithins are phosphatides having the general formula:

onto-00R mitic, oleic, and like components. More specifically, lecithins can be designated as choline esters of fatty acid glyceryl phosphates. They occur in and are recovered from various types of natural materials including egg yolks, legumes such as soybeans, and the like. The lecithins are always associated with the cephalins (sometimes called kephalins). i

The cephalins are colamine esters of higher fatty acid glyceryl phosphates. They are phosphatides and are structurally represented as follows:

In this formula, as in the case of the lecithin formula above, the fatty acid constituents R1 may be saturated or unsaturated, as for example, stearic, palmitic, oleic, and like components. The similarity of the lecithins and the cephalins is evident in their chemical and physical charac-.

teristics. Thus both compounds behave similarly toward many solvents; for example, both are soluble in hydrocarbon oils but insoluble in acetone. Both are waxy in nature and white when pure. Both are easily oxidized on standing in air. The lecithins and the cephalins possess no melting point as both decompose on heating.

Moreover, the various lecithins and cephalins may occur in an alpha or beta form, depending upon the location of the phosphate group in the substituted glycerin molecule. If the phosphate group is present on an end carbon atom, the compound is given the alpha configuration; Whereas, if the phosphate is present on the middle carbon atoms, the composition has the beta configuration. Lecithins and cephalins, therefore, may occur in either the alpha or beta modification and may vary in composition depending upon the fatty acid substituents contained therein.

These various lecithins and cephalins and mixtures of lecithins and cephalins are useful for the purpose of our invention and can be interchangeably used therein. Accordingly, when referring to lecithins and cephalins and mixtures of lecithins and cephalins herein and in the containing different fatty acid substituents and mixtures of the various lecithins and the various cephalins containing minor amounts of other components such as vegetable oils.

Many of the commercially available products sold as lecithin are phosphatide mixtures containing lecithin, cephalin and relatively large amounts of vegetable oils. These mixtures may be used in our invention without any further purification, but the amount used should be based upon the total phosphatide content of the product. If one so desires, such lecithin-cephalin mixtures containing varying amounts of vegetable oils may be purified by extracting the vegetable oils present therein by means of acetone. Also, separation of the lecithins from the cephalins, if desired, may be effected by extraction with cold alcohol, since under this condition, the lecithins are the more alcohol-soluble constituents. However, for the purpose of our invention, this separation is not necessary, since lecithins and cephalins, being phosphatides of a similar chemical nature, are about equally effective whether used alone or in admixture. In carrying out our invention, satisfactory results have been obtained with the lecithincephalin mixtures in the commercially available form known as Gliddol-R (The Glidden Company, Chicago, Illinois). Gliddol-R is derived from soybeans, and contains at least 50 per cent by weight of a mixture of lecithin and cephalin. Other commercial lecithin-cephalin mixtures can also be used.

The amount of phosphatide incorporated into the lubricant compositions of our invention can be varied substantially. As heretofore indicated, the phosphatide is usually present in an amount greater than about 0.25 per cent by weight although smaller amounts may confer improved wick feed flow rate characteristics and other desirable properties to the lubricant composition. In general, it is not necessary to add more than about per cent by weight of phosphatide, since the improved characteristics of the lubricant compositions of our invention will ordinarily be present in compositions containing below this concentration; However, higher amounts of phosphatide may be used without deleterious effect. Particularly good results are obtained with phosphatide concentrations of about 0.5 to 3 per cent by Weight, with the optimum concentration being about 2 per cent by weight.

The ester formed by the reaction of glycerol with mixed acids prepared by the air oxidation of petrolatum can be formed by esterifying glycerol with mixed acids obtained by oxidizing petrolatum with air using conventional methods. We prefer to employ the glyceryl diesters of the mixed aliphatic acids derived from petrolatum by the so-called Burwell oxidation method. A description of this method for making mixed aliphatic acids by the air oxidation of petroleum waxes appears in United States Letters Patent No. 1,768,523 to Arthur W. Burwell. particular, satisfactory results have been obtained with an ester of this type that is commercially available in the form known as Alex 11-1639 (The Alox Corporation, Niagara Falls, New York). An inspection of a typical sample .of this material is as follows:

Gravity, API 210 F 26.7 Viscosity, SUS:

210 F. 580 Neutralization value 14.5 Saponification number 96.5 Water 0.0 n-pentane, insoluble, per cent 3.30 Insoluble resins, per cent 2.89 Benzene, insoluble, per cent 0.31 Inorganic insolubles, per cent 0.16 Ash (oxide), per cent 0.20 Melting point, C 49.0

The amount of ester incorporated into the lubricant compositions of our invention can be varied substantially. Usually, the concentration of ester is about 0.5 to per cent by weight. However, smaller concentrations than 0.5 per cent by weight may sometimes confer advantageous properties and larger concentrations than 10 per cent by weight may be used without deleterious effect. Preferably, the concentration of the ester should be of the order of 2 to 5 per cent by weight, with the optimum concentration being about 2 per cent by weight. It is thus seen that the preferred compositions of our invention contain about 0.5 to 3 per cent by weight of phosphatide and about 2 to 5 per cent by weight of ester, with about 2 per cent by weight being the optimum concentration for each of the above-mentioned components.

The hydrocarbon oils used in the lubricant compositions of our invention comprise a petroleum hydrocarbon oil having a viscosity at 210 F. of about to Saybolt Universal seconds. The inspection for a petroleum hydrocarbon oil base which can be employed in the compositions of our invention is as follows:

Inspection data for petroleum oil base I:

Viscosity, SUS 210 F 79.2 Color, NPA 4.5 Pour point, F 0 Flash point, C. O. C., F. 435 Fire point, F. 505

In addition, additives which improve the oiliness properties of the composition can also be introduced. An example of such an additive in DuPont Ortholeum162 (E. I. DuPont de Nemours and Company, Wilmington, Delaware), which comprises a mixture of lauryl phosphates, predominantly monolaurylphosphate.

In compounding the lubricant compositions of our invention, a variety of procedures can be used. Thus, in one embodiment, the phosphatide and the ester are added to the hydrocarbon oil at a temperature of about F. and the mixture stirred until a clear solution is obtained. Other procedures readily apparent to one skilled in the art can be used for compounding the compositions of our invention.

As an example of the lubricant compositions of our invention, we have prepared a lubricant composition comprising 3 parts by weight of Gliddol-R, 3 parts by weight of Alox L-1639, and 94 parts by weight of petroleum oil base I. In order to illustrate the improved wick feed flow rate characteristics possessed by the compositions of our invention, we have also prepared a composition comprising 3 per cent by weight of Alox L- 1639 in 97 per cent by weight of petroleum oil base I. The wick feed flow rate characteristics of each of the foregoing compositions were determined by method 200.1 of the Federal Standard Stock Catalog, section IV, part 5 VVL791c-98 (May 1945). This test is conducted by inserting a worsted Zephyr wick through a brass tube oilway into a container of oil. The Wick is maintained at a lift of A to /2 inch during the test and the flow rate of the oil is measured at the end of 25 and 48 hours and again at the end of 14 days. The wick feed flow rate characteristics are determined by comparing the flow rate at the end of 14 days with the original flow rate determinations.

The results of the wick feed characteristlc determinations were as follows:

It is seen from the foregoing that the composition comprising 3 per cent by weight of Alox L-1639 and 97 per cent by weight of petroleum oil base I had a wick feed flow rate at the end of 2 weeks of but 18 per cent of the original. However, it is to be noted that this composition possessed excellent water emulsification,-

oiliness and load-carrying properties. These properties were retained by the composition having 3 per cent by weight of GliddolR, 3 per cent by weight of Alox L- 1639 and 94 per cent by weight of petroleum oil base I and moreover, this latter composition also possessed excellent wick feed flow rate characteristics. Thus, after two weeks operation, the Wick feed flow rate of the latter composition remained at 86 per cent of the original.

The optimum lubricant composition of our invention, as heretofore indicated, comprises a composition containing about 2 per cent by weight of the phosphatide and about 2 per cent by weight of the ester. A compo sition of this type prepared with petroleum oil base I produced no noticeable decrease in the wick feed flow rate after two weeks. This composition possessed superior emulsification, extreme pressure, and oiliness properties.

It is to be noted in connection with the wick feed flow rate data presented for the above composition and for Sample B that the federal specifications for a compounded marine engine lubricating oil as set forth in Federal Standard Stock Catalog, section IV, VV-O-54l, February 5, 1935, prescribe a Wick feed fiow rate at the end of two weeks of not less than 30 per cent of the original flow rate. In addition, the specifications for the procurement services of the Army, Navy and Air Force also prescribe a wick feed flow rate retention of 30 per cent of the second days flow during the fourteenth day of the wick feed flow rate test as a requirement for compounded oils of the marine engine oil type (see Symbol 4065 of MIL-L-15019A, July 31, 1950). It is thus seen that the lubricant compositions of our invention greatly surpass the minimum requirements set forth for marine engine compounded lubricating oils by the United States Government.

While the character of the invention has been described in detail, and examples of compositions given, this has been done by Way of illustration only and with the intention that no limitation should be imposed upon the invention thereby. It will be apparent to those skilled in the art that numerous modifications and variations of the illustrations and examples may be effected in the practice of the invention, and accordingly, these modifications and variations should be construed as included within the scope of the claims appended hereto. By way of example, in place of the petroleum hydrocarbon oil which has been disclosed, other petroleum hydrocarbon oils having similar properties can be utilized. Moreover, various relative concentrations of phosphatide to ester within the range of concentrations set forth herein can be employed.

The compositions of our invention comprise excellent lubricants for machines which are affected by water contamination, and/ or in which it is desirable to introduce the oil by means of a syphon wick. Thus, the lubricant compositions of our invention comprise excellent lubricants for marine engines, pneumatic tools, and the like, inasmuch as they form ready stable emulsions with water and possess superior wick feed flow rate characteristics. Moreover, they are possessed of superior oiliness and extreme pressure properties. In addition, the cost of the additives employed in the lubricant compositions of our invention is much less than that of the fatty oils such as rapeseed oil, previously used to confer the afore-mentioned desirable properties upon lubricants of this type.

We claim:

1. A lubricant composition consisting essentially of about 0.5 to 10 per cent by Weight of an ester formed by the reaction of glycerol with mixed acids prepared by the air oxidation of petrolatum, about 0.25 to .5 per cent by weight of a phosphatide, and a petroleum hydrocarbon oil having a viscosity at 210 F. of about to Saybolt Universal seconds.

2. A lubricant composition consisting essentially of about 0.5 to 10 per cent by weight of an ester formed by the reaction of glycerol with mixed acids prepared by the air oxidation of petrolatum, about 0.25 to 5 per cent by weight of a. mixture of a lecithin and a cephalin, and

a petroleum hydrocarbon oil having a viscosity at 210 F.

of about 65 to 90 Saybolt Universal seconds.

3. A lubricant composition consisting essentially of about 2 to 5 per cent by Weight of an ester formed by the reaction of glycerol with mixed acids prepared by the air oxidation of petrolatum, about 0.5 to 3 per cent by weight of a mixture of a lecithin and a cephalin, and a petroleum hydrocarbon oil having a viscosity at 210 F. of about 65 to 90 Saybolt Universal seconds.

4. A lubricant composition consisting essentially of about 2 per cent by weight of an ester formed by the reaction of glycerol with mixed acids prepared by the air oxidation of petrolatum, about 2 per cent by Weight of a mixture of a lecithin and a cephalin, and a petroleum hydrocarbon oil having a viscosity at 210 F. of about 65 to 90 Saybolt Universal seconds.

References Cited in the file of this patent UNITED STATES PATENTS 2,096,390 Burwell Oct. 19, 1937 2,212,020 Hendrey Aug. 20, 1940 2,212,021 Hendrey Aug. 20, 1940 2,222,487 Oosterhaut Nov. 19, 1940 2,373,733 Adams Apr. 17, 1945 OTHER REFERENCES Products from Petroleum for Metal Protection and Lubrication, Alox Corp., Niagara Falls, N. Y., pamphlet published about 1946, 24 pages, p. 22 pertinent.

Lubrication of Industrial and Marine Machinery by Forbes, John Wiley and Son, 2nd printing 1945, pages 142 and 148 pertinent. 

1. A LUBRICANT COMPOSITION CONSISTING ESSENTIALLY OF ABOUT 0.5 TO 10 PER CENT BY WEIGHT OF AN ESTER FORMED BY THE REACTION OF GLYCEROL WITH MIXED ACIDS PREPARED BY THE AIR OXIDATION OF PETROLATUM, ABOUT 0.25 TO 5 PER CENT BY WEIGHT OF A PHOSPHATIDE, AND A PETROLEUM HYDROCARBON OIL HAVING A VISCOSITY AT 210* F. OF ABOUT 65 TO 90 SAYBOLT UNIVERSAL SECONDS. 